⚠️ Apply VAS

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate destructive and non-read-only behavior. Description adds crucial context: charges money (irreversible), and an error does not guarantee no purchase. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Concise, front-loaded with main action and warning. Every sentence provides useful information (purpose, monetary impact, deprecation, prerequisites, error handling). No unnecessary text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema, so description partially compensates by noting response contains service data and charged amount. Covers prerequisites, alternatives, and error handling. Lacks detailed output structure but provides enough context for a complex monetary tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. Description adds value by advising to call items_post_vas_prices for current slug and price, aiding vas_id selection. No additional detail on other parameters, but context improves parameter understanding.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states the tool applies one additional promotion service (VAS) to a listing, using the verb 'applies' and specific resource 'listing'. Differentiates from siblings by explicitly stating deprecation and alternatives: prefer items_apply_vas for one or more services, and use items_put_item_vas_package_v2 for a package.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit guidance: call items_post_vas_prices first for slug and price, confirm with user, and check again on error. Also tells when not to use this tool (for multiple services or packages), directing to alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.